Fluid resistant high temperature hose

ABSTRACT

It has been unexpected found that the fluid resistance of hoses can be greatly enhanced by adding a chlorinated paraffin to a chlorinated polyethylene elastomer or a chlorosulfonated polyethylene elastomer which is used as the tubular inner core layer of the hose. Hoses made using this approach offer the advantage of having improved resistance to modern automotive fluids, provide a longer service life, and better reliability without compromising flexural characteristics or burst strength. Such hoses are comprised of (1) an elastomeric tubular inner core layer defining a lumen, (2) a friction layer, and (3) an elastomeric cover, wherein the elastomeric tubular inner core layer is comprised of (i) a chlorinated elastomer selected from the group consisting of epichlorohydrin, polychloroprene, chlorinated polyethylene and chlorosulfonated polyethylene, (ii) 1 phr to 50 phr of a chlorinated paraffin, and (iii) 30 phr to 120 phr of carbon black.

This is a continuation-in-part of U.S. patent application Ser. No.12/907,250, filed on Oct. 19, 2010, now pending. The teachings of U.S.patent application Ser. No. 12/907,250 are incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

Reinforced hoses are used in a multitude of applications in industry andin consumer products for transporting a wide variety of liquid chemicalsand fluids for various purposes. For instance, such hoses are utilizedin heavy industrial equipment, trucks, and automobiles for transportingtransmission, power steering, and air conditioning fluids. It isimportant for the hose employed in a particular application to beresistant to the fluid which it is intended to convey. This is becauselack of good fluid resistance can lead to a substantial reduction in theservice life of the hose. It is, of course, also critical for the hoseto exhibit adequate fluid resistance while maintaining requisiteflexural properties and burst strength. In recent years new automotivefluids has been introduced which make it much more challenging toprovide the desired combination of fluid resistance, flexuralcharacteristics, and burst strength. There is accordingly a need for ahose that exhibits improved resistance to modern automotive fluids whilemaintaining other needed physical characteristics.

U.S. Pat. No. 6,376,036 discloses an air conditioning hose comprising aninnermost layer, a friction coat layer, an intermediate reinforcinglayer, and an outermost layer, characterized in that: the innermostlayer is comprised of non-plasticized polyamide; the friction coat layeris comprised of a 50/50 weight percent blend of two ethylene propylenediene rubbers, the two rubbers having differing Mooney viscosities, and75 parts by weight of carbon black the intermediate reinforcing layer iscomprised of aramid fibers; and the outermost layer is comprised of ablend of two ethylene acrylic rubbers with differing Mooney viscosities.

U.S. Pat. No. 6,440,512 discloses a hose which is depicted as havinggood chemical resistance without sacrificing flexural properties. Thishose is comprised of (a) an inner core comprising a ternary blend of (1)from 60 to 85 parts by weight of a low density polyethylene; (2) from 10to 20 parts by weight of a polyethylene selected from the groupconsisting of chlorinated polyethylene, chlorosulfonated polyethyleneand mixtures thereof; and (3) from 2 to 25 parts by weight of EPDM; (b)a layer of tensioned reinforcement; and (c) an elastomeric cover.

U.S. Pat. No. 7,614,428 discloses a power steering hose assembly,comprising: a core hose layer; a first reinforcing layer over said corehose layer, wherein said first reinforcing layer is a plastic barrier;an intermediate hose layer over said first reinforcing layer; a secondreinforcing layer over said first reinforcing layer, said secondreinforcing layer having a braid pattern formed in one of a 3-over,3-under pattern or 2-over, 2-under pattern; and, an outer hose layerover said second reinforcing layer. The core hose layer may be made ofchlorosulfonated polyethylene, a chlorosulfonatedpolyethylene/chlorinated polyethylene blend, a hydrogenated nitrilerubber or a nitrile rubber. Further, it may also be made of otherpolymeric material, such as but not limited to polychloroprene,chlorinated polyethylene acrylonitrile-budtadiene, styrene butadiene,polyisoprene, polybutadiene, ethylene-propylene-diene terpolymers,chlorinated polyethylene, or natural rubber polymers. Alternatively, thepolymeric material may comprise thermoplastic elastomers such aspropylene modified with ethylene-propylene rubber, such as Santoprene®block polymers available from Monsanto Corporation; Kraton® polymersavailable from Shell Chemical Company; polyvinyl chloride, etc. U.S.Pat. No. 7,614,428 further indicates that these elastomers may becompounded with other filler, plasticizers, antioxidants, and curesystems to achieve desired properties for particular applications.

U.S. Pat. No. 7,748,412 discloses a hose comprising: a tubular innercore layer defining a lumen with a diameter of about ¼ inch; a tubularouter layer; and, a single reinforcing layer disposed between saidtubular inner core layer and said tubular outer layer, said singlereinforcing layer formed of strands having a 3-over, 3-under braidpattern, said hose having a volumetric expansion not greater than about0.13 cc/ft, not greater than about 0.18 cc/ft, and not greater thanabout 0.29 cc/ft, respectively with about 1000 psi, about 1500 psi, andabout 2900 psi of fluid pressure within said lumen.

U.S. Pat. No. 7,694,695 discloses a controlled expansion hose comprisingan inner tube, a textile reinforcement, and an outer cover; thereinforcement consisting essentially of a plurality of nylon yarns and aplurality of polyester yarns wherein said textile reinforcementcomprises a balanced reinforcing layer of braided, spiraled or wrappedyarns, and wherein the nylon and the polyester yarns are arranged inalternating fashion in the balanced layer. The materials that aredescribed as being useful for the tube, friction layer(s), and/or coverof these hoses include chlorosulfonated polyethylene (“CSM”),chlorinated polyethylene elastomer (“CPE”), nitrile, hydrogenatednitrile, fluoroelastomers, ethylene alpha-olefin elastomers (such asEPM, EPDM, and the like) and the like. U.S. Pat. No. 7,694,695 furtherindicates that these rubber materials may be compounded to includevarious additional ingredients well known in the art, such as fillers,short fibers, plasticizers, antioxidants, antiozonants, stabilizers,process aids, extenders, adhesion promoters, coagents, vulcanizingagents, curatives, and the like.

SUMMARY OF THE INVENTION

The present invention is based on the unexpected discovery that thefluid resistance of hoses can be greatly enhanced by adding achlorinated paraffin to a chlorinated polyethylene elastomer or achlorosulfonated polyethylene elastomer which is used as the tubularinner core layer of the hose. Hoses made using this approach offer theadvantage of having improved resistance to modern automotive fluids,including power steering fluid, transmission fluid, and the like,without compromising flexural characteristics or burst strength.Accordingly, the hoses of this invention provide a longer service lifeand better reliability then hoses made utilizing conventionaltechnology.

The present invention more specifically discloses a hose which iscomprised of (1) an elastomeric tubular inner core layer defining alumen, (2) a friction layer, and (3) an elastomeric cover, wherein theelastomeric tubular inner core layer is comprised of (i) a chlorinatedelastomer selected from the group consisting of epichlorohydrin,polychloroprene, chlorinated polyethylene and chlorosulfonatedpolyethylene, (ii) 1 phr to 50 phr of a chlorinated paraffin, and (iii)30 phr to 120 phr of carbon black. It is typically preferred for thechlorinated elastomer to be chlorinated polyethylene or chlorosulfonatedpolyethylene.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially broken away perspective view depicting a hosewhich illustrates one embodiment of this invention.

FIG. 2 is a cross-sectional view taken generally along line 2-2 of FIG.1.

FIG. 3 is a partially broken away perspective view depicting a hosewhich illustrates another embodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION

These hoses can be employed in a variety of automotive applications,such as hoses for automatic transmission fluid, air conditioningrefrigerant, engine oil, and the like. The dimensions of the lumenincorporated into such hoses will, of course, depend upon the specificapplication for which the hose will be used. In many applications thehose will have a lumen (an inside diameter) which is within the range ofabout 10 mm to about 15 mm. The hoses of this invention will typicallyhave an inside diameter which is within the range of 11 mm to 13 mm andwill frequently have an inside diameter which is within the range of11.5 mm to 13.5 mm.

As depicted in FIGS. 1-3, the hoses of this invention are comprised ofan elastomeric tubular inner core layer 12 defining a lumen 13 which isthe innermost layer of the hose 10, a friction layer 14 which ispositioned outwardly from the elastomeric tubular inner core layer 12,and an elastomeric cover 30 which is positioned outwardly from thefriction layer 14 and forms the outermost portion of the hose. Theelastomeric tubular inner core layer 12 is frequently referred to in theart as simply the “tube” or as simply as the “core.” The friction layer14 is also known in the art as a reinforcing layer or as a reinforcementlayer which typically includes a natural or synthetic textile yarn ormetallic wire reinforcement. The hoses of this invention can alsoinclude additional layers such as a barrier layer and/or additionalreinforcing layers if desired. However, the hoses of this invention canconsist solely of the elastomeric tubular inner core layer 12, thefriction layer 14, and the elastomeric cover 30.

The elastomeric tubular inner core layer 12 of the hoses of thisinvention are comprised of (i) a chlorinated elastomer selected from thegroup consisting of epichlorohydrin, polychloroprene, chlorinatedpolyethylene and chlorosulfonated polyethylene, (ii) 1 phr (parts byweight per hundred parts by weight of rubber) to 50 phr of a chlorinatedparaffin, and (iii) 30 phr to 120 phr of carbon black. The chlorinatedparaffins that are incorporated into the elastomeric tubular inner corelayer 12 have a degree of chlorination which is within the level of 40percent to 70 percent. The chlorinated paraffin will typically containfrom 45 weight percent to 65 weight percent chlorine and will moretypically contain 50 weight percent to 55 weight percent chlorine. Thechlorinated paraffin can be a short chain paraffin containing from about10 to 13 carbon atoms, a medium chain paraffin containing from 14 to 17carbon atoms, or a long chain paraffin containing more than 17 carbonatoms. The viscosity of the chlorinated paraffin increases withincreasing chain length. However, the level of chlorination has a muchmore pronounced effect on viscosity than does the length of thecarbon-carbon chain in the chlorinated paraffin.

The chlorinated paraffin will be incorporated into the tube 12 of thehoses of this invention at a level which is within the range of 1 phr to50 phr. The chlorinated paraffin will typically be incorporated into thetube 12 at a level which is within the range of 5 phr to 48 phr and willmore typically be incorporated into the tube 12 at a level which iswithin the range of 10 phr to 45 phr. The chlorinated paraffin willpreferably be incorporated into the tube 12 at a level which is withinthe range of 15 phr to 42 phr and will more preferably be incorporatedinto the tube 12 at a level which is within the range of 20 phr to 40phr. The chlorinated paraffin will most preferably be incorporated intothe tube 12 at a level which is within the range of 25 phr to 35 phr.

Chlorinated polyethylene that can be used in the practice of thisinvention can be in the form of finely-divided particles which typicallymeet four physical property criteria. First, the chlorinatedpolyethylene will typically have a weight average molecular weight whichis within the range of about 40,000 to about 300,000. Second, thechlorinated polyethylene will also typically have a chemically combinedchlorine content of from about 20 to about 48 percent by weight ofpolymer. Third, the chlorinated polyethylene will typically have a 100percent modulus, measured in accordance with ASTM Test D-412, from about0.5 to about 4.8 MPa. Fourth, the chlorinated polyethylene willtypically have a heat of fusion which is within the range of about 0 toabout 15 calories per gram, and will preferably have a heat of fusionwhich is within the range of about 0 to about 10 calories per gram.Commercially available chlorinated polyethylenes that are suitable foruse in the present invention include but are not limited to thoseobtained from Dow Chemical Company under the designation Tyrin™ 3611Pand Tyrin™ CM0136.

The chlorosulfonated polyethylene useful in this invention is typicallya material having from about 20 to about 48 weight percent chlorine andfrom about 0.4 to about 3.0 weight percent sulfur. Typical preparationsof chlorosulfonated polyethylene are disclosed in U.S. Pat. No.2,586,363 and U.S. Pat. No. 2,503,252. Commercially availablechlorosulfonated polyethylenes which may be used in the presentinvention include but are not limited to those obtained from E I DuPontde Nemours, Inc, under the designation Hypalon™, such as Hypalon 20,Hypalon 40, Hypalon 40 HS, Hypalon 4085 and Hypalon HPG 6525.

The carbon black will be incorporated into the elastomeric tubular innercore layer 12 of the hoses of this invention at a level which is withinthe range of about 30 phr to about 120 phr. The carbon black willtypically be incorporated into the tube 12 of the hoses of thisinvention at a level which is within the range of about 60 phr to about115 phr and will more typically be incorporated at a level which iswithin the range of about 70 phr to about 110 phr. The carbon black willpreferably be incorporated into the tube 12 at a level which is withinthe range of about 90 phr to about 110 phr.

The carbon black used in the practice of this invention may include anyof the commonly available, commercially-produced carbon blacks, butthose having a surface area (EMSA) of at least 20 m²/g and morepreferably at least 35 m²/g up to 200 m²/g or higher are preferred.Surface area values used in this application are those determined byASTM test D-1765 using the cetyltrimethyl-ammonium bromide (CTAB)technique. Among the useful carbon blacks are furnace black, channelblacks and lamp blacks. More specifically, examples of the carbon blacksinclude super abrasion furnace (SAF) blacks, high abrasion furnace (HAF)blacks, fast extrusion furnace (FEF) blacks, fine furnace (FF) blacks,intermediate super abrasion furnace (ISAF) blacks, semi-reinforcingfurnace (SRF) blacks, medium processing channel blacks, hard processingchannel blacks and conducting channel blacks. Other carbon blacks whichmay be utilized include acetylene blacks. Mixtures of two or more of theabove carbon blacks can be used in preparing the rubber formulationutilized in making the tubes of the hoses of this invention. Typicalvalues for surface areas of usable carbon blacks are summarized in thefollowing table.

Carbon Black ASTM Designation (D-1765-82a) Surface Area (D-3765) N-110126 m²/g  N-220 111 m²/g  N-339 95 m²/g N-339 83 m²/g N-550 42 m²/gN-660 35 m²/g

The tube of the hoses of this invention can also include a variety ofother compounding ingredients including fillers (in addition to carbonblack), plasticizers, reinforcing agents, fillers, peptizing agents,pigments, stearic acid, accelerators, crosslinking agents, antiozonants,antioxidants, processing oils, activators, initiators, curatives,plasticizers, waxes, prevulcanization inhibitors, extender oils and thelike that are designed to attain desired characteristics. For instance,the tube formulation will typically contain a peroxide cure system or athiodiazole cure system. Peroxide cure systems are typically preferredto attain a higher level of heat resistance. It should be noted that therubber formulation is typically void of zinc compounds.

In those instances, when the hose will be used to convey flammablefluids, electrically conductive blacks may be used. Noncarbon blackfillers which may be used include talc, clay, calcium carbonate, silicaand the like. Noncarbon black fillers, such as silica, may be used in anamount ranging from about 5 phr to 150 phr. The preferred noncarbonblack filler is silica. Oil dispersions containing such fillers may alsobe used. Organosilanes such as 3,3′ bis(triethoxysilylpropyl)tetrasulfide may be used in amounts ranging from 0.1 to 20 phr. Suitableexamples of such organosilanes are disclosed in U.S. Pat. No. 4,128,438the teachings of which are incorporated herein by reference in theirentirety. Representative of the antidegradants which may be in theternary blend composition include microcrystalline wax, paraffinic wax,monophenols, bisphenols, thiobisphenols, polyphenols, hydroquinonederivatives, phosphites, phosphate blends, thioesters, naphthylamines,diphenol amines, substituted and unsubstituted diaryl amine derivatives,diarylphenylenediames, para-phenylene diamines, quinolines and blendedamines. Antidegradants are generally used in an amount ranging fromabout 0.1 phr to about 10 phr with a range of from about 2 phr to 6 phrbeing preferred. Representative of processing aids which may be used inthe rubber composition of the present invention include activateddithio-bisbenzanilide, poly-para-dinitrosobenzene, xylyl mercaptans,aliphatic-naphthenic aromatic resins, polyethylene glycol, calciumstearamide, petroleum oils, vulcanized vegetable oils, pine tar,phenolic resins, synthetic oils, petroleum resins, polymeric esters androsins. These processing oils may be used in a conventional amountranging from about 0 phr to about 140 phr. Long chain fatty acids, suchas stearic acid, are representative examples of initiators that can beused. Initiators are generally used in a conventional amount rangingfrom about 1 phr to 4 phr. Additional additives which may be used aspart of the cure package include calcium oxide and magnesium oxide.These additives are conventionally used in amounts ranging from 0.1 phrto 25 phr. Crosslinkers such as triallylisocyanurate and triazine-basedmaterials may be used in amounts ranging from 0.25 phr to 6 phr.

The peroxides that can be used in the practice of this invention includethose that are normally used in the industry. For example, peroxidessuch as dicumyl peroxide, α,α′-bis(t-butylperoxide)diisopropylbenzene,benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane,2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, methylethyl ketone peroxide, cyclohexanoneperoxide, cumene hydroperoxide, pinane hydroperoxide, p-menthanehydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide and n-butyl4,4-bis(t-butylperoxy)valerate. The most preferred peroxide curative isdicumyl peroxide. From 1 to about 10 phr of peroxide are typicallyutilized.

The friction layer 14 in the hoses of this invention is essentially alayer of tensioned reinforcing members 16 and 18. Such reinforcement isknown to those skilled in the art and may consist of spiraled, woven,knitted, cabled or braided reinforcement. Such reinforcements aretypically derived from cotton, polyester, nylon, metal, rayon or aramidand have a denier value which is within the range of about 1500 to about2000. When the reinforcement is metal, it may be steel, brass-coatedsteel, zinc-coated or galvanized steel. The reinforcement is preferablyspirally wound or braided yarns under sufficient tension to improve thestrength of the hose structure. In another embodiment of this inventionthe reinforcement is a woven fabric. If the reinforcement isspiral-wound, the reinforcement layer is preferably spirally wrapped atangles such that the flexing of the hose will not result in collapse orkinking. An angle such as from 0° to 89.9° with respect to thecenterline of the hose may be used. Most preferably, a neutral angle of54° 44′ or below is used for the spiral wraps. When the reinforcement isa fabric, it is conventionally in the form of a rubber-impregnatedfabric. Combinations of two or more types of reinforcement may be used.

The third element required in the hose of the present invention is anelastomeric cover 30. This elastomeric cover 30 may be extruded orspirally wrapped over the underlying layer, which may be the frictionlayer 14 or, various other optional layers. The elastomers which may beused to form the cover for the hose of the present invention includethose known to those skilled in the art such as chlorosulfonatedpolyethylene, chlorinated polyethylene, acrylonitrile-butadienerubber/PVC blends, epichlorohydrin, EPDM, chloroprene, EVA and EVM.Preferably, the elastomer used in the cover is chlorinated polyethylene,EPDM or a NBR/PVC blend. The thickness of the elastomeric cover 30obviously depends upon the desired properties of the hose and theelastomer that is used. Generally speaking, the thickness of theelastomeric cover 30 will range from about 0.5 mm to about 4.0 mm, witha range of from 1.0 mm to being 2.5 mm being preferred.

In addition to the tube 12, the friction layer 14, and the elastomericcover 30, the hoses of this invention can also contain other optionallayers. For example, a barrier layer can optionally be incorporated intothe hose 10 on the outside of the inner core 12. Such barrier layer maycomprise one or more layers of films. Such barrier layers can be filmswhich are comprised of low density polyethylene, linear low densitypolyethylene, high density polyethylene, copolymer polypropylene,homopolymer polypropylene and mixtures thereof. Additional materialswhich can be used as barrier films include fluoroplastics andfluoropolymers including, for example, the TEFLON® and TEFZEL® family offluoroplastics and fluoropolymers such as TEFLON PTFE(polytetrafluoroethylene), TEFLON FEP (fluorinated ethylene-propylene),TEFLON PFA (perfluoroalkoxy), TEFLON AF and TEFZEL polymers. Anotherclass of polymeric materials which can optionally be used in barrierlayers includes terpolymer derived from tetrafluoroethylene,herafluoro-propylene and vinylidine fluoride (THV). THV is commerciallyavailable from the 3M Company under the designations THV 200, THV 300,THV 400 and THV 500. The thickness of such optional barrier layers istypically within the range of from about 0.025 to 0.30 mm, with athickness of from 0.1 to 0.2 mm being preferred.

Dispersed on the outside of the barrier layer may be a first layer ofanother polymer. Such polymer may be comprised the same ternary blend ofpolymers as is used the inner core. The thickness of this first layerwhich directly interfaces with the barrier layer may vary. Generallyspeaking, the thickness of this first layer will range of from about 0.2mm to about 4.0 mm with a range of from about 0.4 mm to about 0.8 mmbeing preferred.

FIG. 1 and FIG. 2 illustrate an embodiment of this invention wherein thefirst and second reinforcing members 16, 18 of the single reinforcinglayer 14 are braided in a pattern such that each first reinforcingmember 16 crosses over an oppositely wound second reinforcing member 18,and then passes under an adjacent, oppositely wound reinforcing member18 in succession. This braid pattern is referred to herein as a 1-over,1-under braid pattern. The first and second reinforcing members 16, 18may be wound, for example, using strands having denier values of about1500, with four ends and 24 carriers of the rotary braiding machine tothereby define a total reinforcement provided by the single reinforcinglayer 14 of about 144,000 denier. Other combinations of strand deniervalue, number of ends and number of carriers are alternativelycontemplated to yield a single reinforcing layer 14 providing a totalreinforcement not greater than about 144,000. The resulting braidpattern of single reinforcement layer 14 may yield a total coverage ofthe underlying surface (e.g., the inner core layer 12) in the range ofabout 75% to about 100%.

The specific arrangement of the strands of the first and secondreinforcing members 16, 18 in a 1-over, 1-under braid pattern permitsformation of a single reinforcing layer 14 that has a substantiallysmooth appearance. This smooth appearance, in turn, yields a smoothappearance of the hose 10. Moreover, the specific arrangement preventsor at least minimizes bleed-through of any adjacent layers of the hose10 through single reinforcing layer 14. For example, the chosenarrangement of single reinforcing layer 14 may prevent or minimizebleed-through of a rubber-based material extruded over singlereinforcing layer 14. The chosen arrangement, moreover, determines otherproperties such as the amount of flexibility of the resulting hose 10.

The hose 10 may further include an outer layer 30 formed over the singlereinforcing layer 14, for example, by extruding the outer layer 30 overthe single reinforcing layer 14. The outer layer 30 protects the hose 10and is formed from a material suited for use in an application for whichthe hose 10 will be used. As a non-limiting example, the outer layer 30may be formed from any of the various materials described above for theinner core layer 12. The thickness of outer layer 30 is suitably chosenfor a specific application. For example, and without limitation, outerlayer 30 may have a thickness in the range from about 1.2 mm to about1.5 mm. The thickness of outer layer 30, along with the dimensions ofthe inner core layer 12 and those of single reinforcing layer 14,defines an outer diameter of the outer layer 30. For example, andwithout limitation, outer layer 30 may have an outer diameter in therange from about 11.5 mm to about 12.5 mm.

FIG. 3 illustrates another embodiment of this invention wherein thefriction layer 14 is comprised of a first yarn layer 17 which isspiraled onto the tube from one direction and a second yarn layer 19being spiraled over the first yarn layer from the other direction. Infriction layers of this type the reinforcing members 17 and 19 aresimply spirally wound onto the tube 12 of the hose 10 without beingbraided. For a variety of reasons this type of friction layer 14 isnormally preferred in the hoses of this invention.

This invention is illustrated by the following examples that are merelyfor the purpose of illustration and are not to be regarded as limitingthe scope of the invention or the manner in which it can be practiced.Unless specifically indicated otherwise, parts and percentages are givenby weight.

Examples 1-4

In this series of experiments various rubber formulations for theelastomeric tubular inner core layer for the hoses of this inventionwere formulated cured and tested. These formulations were made by firstmixing various ingredients in a non-productive mixing stage. In theprocedure used 85 phr of a chlorinated polyethylene elastomer (30percent chlorine content), 15 phr of ethylvinyl acetate, 95 phr ofcarbon black, an ester plasticizer in the amount shown in Table 1, 20phr of magnesium oxide, 3.10 phr of polyethylene wax, 0.30 of trimethylquinolin antioxidant, 1.00 phr of a hindered phenolic antioxidant, andthe amount of chlorinated paraffin indicated in Table 1 were mixedtogether. As can be seen the total amount of ester plasticizer added wasreduced as the amount of chlorinated paraffin was increased to maintaina constant hardness of the vulcanizate. Then, the non-productive mixturewas further mixed with 7.90 phr of dicumyl peroxide (60% active) and2.65 phr of Triallyl Cyanurate (72% active) coagent in a productivemixing stage. The productive compound samples were then cured at atemperature of 320° F. for a 40 minute cure time.

The initial tensile strength, elongation, and Shore A hardness of thecured samples was then measured and additional samples were thenimmersed in Chrysan Type A fluid at 275° F. (135° C.) and maintained atthat temperature for 168 hours. Then, the physical properties of theaged samples were measured and compared with original properties.Tensile strength and elongation were measured according to ASTM D-412and Shore A hardness was measured according to ASTM D-2240. The resultsof this testing is also reported in Table 1.

TABLE 1 Example 1 2 3 4 Level of Chlorinated none 10.0 20.0 30.0Paraffin (phr) Ester plasticizer (phr) 45.0 35.0 25.0 15.0 TensileStrength (psi/ 1186/8.2 1781/12.3 1951/13.5 2248/15.5 MPa) Elongation 97% 164% 173% 185% Shore A Hardness 67 60 63 64 % Change in Tensile−52% −23% −17%  −7% Strength % Change in Elongation −55% −27% −19% −11%

As can be seen from Table 1, the incorporation of the chlorinatedparaffin into the rubber formulations for the elastomeric tubular innercore layer for the hoses of this invention resulted in much lowerchanges in tensile strength and elongation after being aged in the fluidat elevated temperature. This is indicative of the hoses of thisinvention which have a chlorinated paraffin in the tube layer offeringbetter resistance to the fluid and consequently better service life.

Examples 5-8

In this series of experiments various rubber formulations for theelastomeric tubular inner core layer for the hoses of this inventionwere formulated, cured and tested. These formulations were made by firstmixing various ingredients in a non-productive mixing stage. In theprocedure used 75 phr of a chlorosulfonated polyethylene (36 percentchlorine content), 25 phr of a chlorosulfonated polyethylene (30 percentchlorine content), 75 phr of carbon black, 25 phr of Kaolin clay, anester plasticizer in the amount shown in Table 2, 20 phr of magnesiumoxide, 3.0 phr of polyethylene wax, 0.30 of trimethyl dihydroquinolineantioxidant, the level of a hindered phenolic antioxidant shown in Table2, and the amount of chlorinated paraffin indicated in Table 2 weremixed together. As can be seen the total amount of ester plasticizeradded was reduced as the amount of chlorinated paraffin was increased tomaintain a constant hardness of the vulcanizate. Then, thenon-productive mixture was further mixed with 5.00 phr of dicumylperoxide (60% active) and 5.60 phr of a Triallyl Cyanurate (72% active)coagent in a productive mixing stage. The productive compound sampleswere then cured at a temperature of 320° F. for a 40 minute cure time.

The initial tensile strength, elongation, and Shore A hardness of thecured samples was then measured and additional samples were thenimmersed in Chrysan Type A fluid at 275° F. (135° C.) and maintained atthat temperature for 168 hours. Then, the physical properties of theaged samples were measured and compared with original properties.Tensile strength and elongation were measured according to ASTM D-412and Shore A hardness was measured according to ASTM D-2240. The resultsof this testing is also reported in Table 1.

TABLE 2 Example 5 6 7 8 Level of Chlorinated Paraffin None 15 25 25(phr) Hindered phenolic antioxidant* None None None 1 (phr) Esterplasticizer (phr) 25.0 10.0 0.0 10.0 Tensile Strength (psi/MPa) 19382471 2661 2581 Elongation 80 113 134 130 Shore A Hardness 76 76 76 76 %Change in Tensile Strength −26.2% −10.8%  −5.6%  −2.2% % Change inElongation −46.9% −29.7% −17.1% −22.8% Hardness change (pts) −4 −4 −6 −5*Irganox ® MD1024N,N′-bis-β-(3,5-di-tert-butyl-4-hydroxyphenol)-propionyl hydrazidehindered phenolic antioxidant made by Ciba Specialty Chemicals.

As can be seen from Table 2, the incorporation of the chlorinatedparaffin into the rubber formulations for the elastomeric tubular innercore layer for the hoses of this invention resulted in much lowerchanges in tensile strength and elongation after being aged in the fluidat elevated temperature. This is indicative of the hoses of thisinvention which have a chlorinated paraffin in the tube layer offeringbetter resistance to the fluid and consequently better service life.

While certain representative embodiments and details have been shown forthe purpose of illustrating the subject invention, it will be apparentto those skilled in this art that various changes and modifications canbe made therein without departing from the scope of the subjectinvention.

What is claimed is:
 1. A hose having improved resistance to powersteering fluid and transmission fluid which is comprised of (1) anelastomeric tubular inner core layer defining a lumen, (2) a frictionlayer, and (3) an elastomeric cover, wherein the elastomeric tubularinner core layer is comprised of (i) a chlorinated elastomer selectedfrom the group consisting of epichlorohydrin, chlorinated polyethyleneand chlorosulfonated polyethylene, (ii) 15 phr to 50 phr of achlorinated paraffin, and (iii) 30 phr to 120 phr of carbon black. 2.The hose as specified in claim 1 wherein the elastomer is chlorinatedpolyethylene.
 3. The hose as specified in claim 1 wherein the elastomeris chlorosulfonated polyethylene.
 4. The hose as specified in claim 1wherein the chlorinated paraffin has a chlorine content of 40 weightpercent to 70 weight percent.
 5. The hose as specified in claim 4wherein the chlorinated paraffin is present in the elastomeric tubularinner core layer at a level which is within the range of 5 phr to 48phr.
 6. The hose as specified in claim 1 wherein the carbon black ispresent at a level which is within the range of 60 phr to 115 phr. 7.The hose as specified in claim 1 wherein the friction layer is comprisedof 2 layers of yarn which are spirally wound.
 8. The hose as specifiedin claim 1 wherein the chlorinated paraffin has a chlorine content of 50weight percent to 70 weight percent.
 9. The hose as specified in claim 8wherein the chlorinated paraffin is present in the elastomeric tubularinner core layer at a level which is within the range of 10 phr to 45phr.
 10. The hose as specified in claim 9 wherein the carbon black ispresent at a level which is within the range of 70 phr to 110 phr. 11.The hose as specified in claim 1 wherein the chlorinated paraffin has achlorine content of 50 weight percent to 55 weight percent.
 12. The hoseas specified in claim 11 wherein the chlorinated paraffin is present inthe elastomeric tubular inner core layer at a level which is within therange of 15 phr to 42 phr.
 13. The hose as specified in claim 12 whereinthe carbon black is present at a level which is within the range of 90phr to 100 phr, and wherein the friction layer is comprised of 2 layersof yarn which are spirally wound.
 14. The hose as specified in claim 1wherein the elastomeric tubular inner core layer is cured with aperoxide curing agent.
 15. The hose as specified in claim 1 wherein theelastomeric tubular inner core layer is void of zinc compounds.
 16. Thehose as specified in claim 14 wherein the peroxide curing agent isselected from the group consisting of dicumyl peroxide,α,α′-bis(t-butylperoxide)diisopropylbenzene, benzoyl peroxide,2,4-dichlorobenzoyl peroxide, 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane,2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, methylethyl ketone peroxide, cyclohexanoneperoxide, cumene hydroperoxide, pinane hydroperoxide, p-menthanehydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide and n-butyl4,4-bis(t-butylperoxy)valerate.
 17. The hose as specified in claim 1wherein the friction layer is comprised of braided yarns.
 18. The hoseas specified in claim 1 wherein the elastomeric tubular inner core layeris cured with a thiodiazole cure system.
 19. A hose having improvedresistance to power steering fluid and transmission fluid which iscomprised of (1) an elastomeric tubular inner core layer defining alumen, (2) a friction layer, wherein the friction layer consists of arubber-impregnated fabric, wherein the fabric is a woven, knitted, orbraided fabric, and wherein the fabric is selected from the groupconsisting of cotton fabrics, polyester fabrics, nylon fabrics, rayonfabrics, and aramid fabrics, and (3) an elastomeric cover, wherein theelastomeric tubular inner core layer is comprised of (i)epichlorohydrin, (ii) 15 phr to 50 phr of a chlorinated paraffin, and(iii) 30 phr to 120 phr of carbon black, wherein the elastomeric tubularinner core layer is void of noncarbon black fillers.